American Society of Civil Engineers

Pressure-Flow Relationships for Distribution System Connections

by Srinivasa Lingireddy, (Assoc. Prof. of Civ. Engrg., Univ. of Kentucky, Lexington, KY 40506-0281) and Don J. Wood, (Prof. of Civ. Engrg., Univ. of Kentucky, Lexington, KY)

Journal of Hydraulic Engineering, Vol. 126, No. 10, October 2000, pp. 786-791, (doi:

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Document type: Technical Note
Abstract: The suggested practice of using single point test data to construct a “straight line” (i.e., hydraulically scaled) water supply plot is investigated herein. It is shown that this widely used practice may lead to large errors in determining the available pressure at a connection for a design flow condition. It is further shown that using a second test point to construct a quadratic water supply plot can produce far better accuracy. Inaccurate plots of the available pressures can lead to erroneous fire flow predictions and improperly designed fire protection sprinkler systems. This raises safety concerns in addition to poorly designed facilities.

ASCE Subject Headings:
Water distribution systems
Water supply